Schedule III - Real Estate and Accumulated Depreciation - Rollforward of Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
SEC Schedule III, Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance as of the beginning of the year	$ 383,966	$ 308,173	$ 235,157
Additions	101,194	87,854	75,656
Dispositions	(10,937)	(12,061)	(2,640)
Balance as of the end of the year	474,223	383,966	308,173
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Accumulated depreciation lease intangibles	$ 201,900	$ 166,000	$ 137,800
Tenant Improvements | Minimum
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful life	1 month
Tenant Improvements | Maximum
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful life	240 months
Furniture and Fixtures
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful life	5 years